Synthesis of Mesoporous Silica Molecular Sieves via a NovelTemplating Scheme

Mesoporous silica molecular sieves have been synthesized under mild conditions by using in situ prepared N,N-dimethyldodecylamine oxide as template.

Immobilization of Trehalose Synthase on Mesoporous Molecular Sieve

[ Objective] This study aimed to explore the immobitizatian of trehalose synthase on mesoporous molecular sieves. [ Method] With trehalose synthase produced by genetically engineered bacteria as experimental material, rnesoporous molecular sieve MCM-41 was used as a carrier for immobilization of trehalase syn- thase. Properties of trehalose synthase before and after immobilization were compared. [ Result ] Trehalose synthase could be immohihzed on mesoporous molecular sieve MCM-41 by using physical adsorption method. Immobilization of trehalose synthase achieved the best effect at pH 3.0, with enzyme amount of 62.5 mg/g and immobilization duration of 12 h. Compared with the free u, ehalose synthase, immobilized trehalose synthase showed significantly improved pH stability and thermal stability with repeatable operation, which was conducive to the utilization and storage of enzyme. [ Conclusion] This study provided theoretical basis for the devel- opment of new immobilized trehalose synthase.

Synthesis of Mesoporous Molecular Sieve MCM-41 in Extremely Dense System

Mesoporous molecular sieve MCM-41 has been synthesized in the extremely dense system (with H2O/Si<10) and characterized by XRD, N-2 adsorption isotherm as well as probe reactions of cracking of cumene and isomerization of o-xylene.

Mesoporous molecular sieve confined phase change materials with high absorption,enhanced thermal conductivity,and cooling energy charging/discharging capacity

The biggest challenge for organic phase change materials(PCMs)used in cold energy storage is to maintain high heat storage capacity while reducing the leakage risk of PCMs during the phase transition process.This is crucial for expanding their applications in the more demanding cold storage field.In this study,novel formstable low-temperature composite PCMs are prepared with mesoporous materials,namely SBA-15 and CMK-3(which are prepared using the template method),as supporting matrices and dodecane as the PCM.Owing to the combined effects of capillary forces within mesoporous materials and interactions among dodecane molecules,both dodecane/SBA-15 and dodecane/CMK-3 exhibit outstanding shape stability and thermal cycling stability even after 200 heating/cooling cycles.In comparison to those of dodecane/SBA-15,dodecane/CMK-3 exhibits superior cold storage performance and higher thermal conductivity.Specifically,the phase transition temperature of dodecane/CMK-3 is-8.81℃ with a latent heat of 122.4 J·g^(-1).Additionally,it has a thermal conductivity of 1.21 W·m^(-1)·K^(-1),which is 9.45 times that of dodecane alone.All these highlight its significant potential for applications in the area of cold energy storage.

π-Complexation Mesoporous Adsorbents Cu-MCM-48 for Ethylene-Ethane Separation

Copper incorporated MCM-48 molecular sieve adsorbents with different Cu content have been hydrothermally synthesized. The samples have been characterized by various physicochemical methods, including X-ray diffraction （XRD）, nitrogen adsorption （N2） and X-ray photoelectron spectroscopy （XPS）. The results reveal that Cu-MCM-48 with mass fraction of copper up to 10 % can still retain the uniform mesoporous framework of MCM-48. The copper in the framework of MCM-48 was easily auto-reduced to Cu（I） in N2 at high temperature, which did not alter the mesoporous structure of MCM-48. The adsorption equilibrium isotherms of ethylene and ethane on these molecular sieve adsorbents have been measured at 30℃. At 100 kPa, the adsorption capacities of ethylene on 5Cu-MCM-48 and 10Cu-MCM-48 are higher than those on MCM-48. The 10Cu-MCM-48 molecular sieve adsorbent has a higher selective adsorption ratio of ethylene to ethane, the separation factor is 3.8, and the amount of ethylene adsorbed is 11.1 ml·g ^-1.

Titanium-Containing Mesoporous Materials: Synthesis and Application in Selective Catalytic Oxidation

Titanium-containing mesoporous molecular sieves are of great significance in selective catalytic oxidation processes with bulky molecules. Recent researches and developments on the designing and synthesis of Ti-containing mesoporous materials have been reviewed. Various strategies for the preparation of Ti-containing mesoporous materials, such as direct synthesis and post-synthesis, are described. Modifications of Ti-containing mesoporous materials by surface-grafting and atom-planting are also discussed. All approaches aimed mainly at the improving of the stability, the hydrophobicity, and mostly the catalytic activity. Structural and mechanistic features of various synthetic systems are discussed. Ticontaining mesoporous materials in liquid phase catalytic oxidation of organic compounds with H2O2 as an oxidant is briefly summarized, showing their broad utilities for green synthesis of fine chemicals by catalytic oxidative reactions.

Adsorption Mechanisms of Mesoporous Adsorbents in Solutions

Sieve effect, complexation, ionic exchange, electrostatic interaction, hydrogen bonding, hydrophobic interaction, and molecular recognition based on molecular imprinting are comprehensively discussed.

ENCAPSULATION OF STRONG SOLID ACID NANOPARTICLES IN MESOPOROUS CHANNEL HOSTS

Mesoporous molecular sieve with Al-promoted sulfated rirconia (SZA) based strong solid acid nano-particles within its mesoporous channels was synthesized by using a one-step incipient wetness impregnation method with zirconium sulfate and aluminum sulfate as the precursors. The assemblies of SZA/MCM-41 were obtained by thermal decomposition of the precursors in air.The resultant composite was characterized with various techniques such as nitrogen physisorption, X-ray diffraction, SEM and TEM. It was shown that the well-ordered channels of MCM-41 arranged in hexagonal arrays as well as the hollow tubular morphology was retained. The strong solid acid nanoparticles were isolated born each other and highly, dispersed in the channels. Nitrogen sorption showed the expected decrease in pore volume. The catalytic activity of SZA/MCM-41 composite in the isomerization of n-butane was dramatically improved in comparison to bulk SZA or SZA/silica.

Mesoporous molecular sieve-based materials for catalytic oxidation of VOC: A review

As the main contributor of the formation of particulate matter as well as ozone, volatile organic compounds(VOCs) greatly affect human health and the environmental quality. Catalytic combustion/oxidation has been viewed as an efficient, economically feasible and environmentally friendly way for the elimination of VOCs. Supported metal catalyst is the preferred type of catalysts applied for VOCs catalytic combustion because of the synergy between active components and support as well as its flexibility in the composition. The presence of support not only plays the role of keeping the catalyst with good stability and mechanical strength, but also provides a large specific surface for the good dispersion of active components, which could effectively improve the performance of catalyst as well as decrease the usage of active components, especially the noble metal amount. Mesoporous molecular sieves, owing to their large surface area, unique porous structures, large pore size as well as uniform pore-size distribution, were viewed as superior support for dispersing active components. This review focuses on the recent development of mesoporous molecular sieve supported metal catalysts and their application in catalytic oxidation of VOCs. The effect of active component types, support structure, preparation method, precursors, etc. on the valence state, dispersion as well as the loading of active species were also discussed and summarized. Moreover, the corresponding conversion route of VOCs was also addressed.This review aims to provide some enlightment for designing the supported metal catalysts with superior activity and stability for VOCs removal.

Structrue and Characteristics of Mesoporous Silica Synthesized in Acid Medium and Its Reaction Mechanism

Structrue and pore characteristics of the mesoporous silica synthesized in acid medium were studied by means of XRD, HRTEM, BET, FT-IR, DSC-TGA, and the reaction mechanism was also investigated deeply. The results show that mesopores in the sample possess hexagonal arrays obviously, whereas the structure of silica matrix is amorphous. The results also show that the acting mode of silica and CTMA+ inside the mesopores was chemical bonding force. The structure of mesoporous silica was mainly dependent on the aggregational condition of micelle of CTMA+ as well as their liquid-crystallized status. In addition, condensation and dehydration of silicate radicals were accompanied in the process of calcination, which resulted in the mesoporous structure ordered in local range and the pore sizes largening.

Large Pore Mesoporous MCM-41 Templated from Cetyltriethylammonium Bromide

Following hydrothermal synthesis process, MCM-41 was synthesized by using cetyltriethylammonium bromide as templating agent. The experimental results showed that MCM-41 with pore diameter in the range of 4-7 nm can be obtained by adjusting nsurf/nsi. It was proved that cetyltriethylammonium bromide is an effective templating agent for increasing pore diameter of molecular sieve MCM-41.

有机硅烷对介孔Y型分子筛理化特性及费托性能影响研究

为了合成对汽油段、柴油段产物有高选择性的催化剂载体,以多种有机硅烷为模板剂原位合成了高结晶度介孔Y型分子筛,考察了硅烷剂浓度以及有机硅烷剂中的取代基对Y型分子筛性能的影响,并以合成的介孔分子筛为载体通过浸渍法负载钴制备了催化剂,考察了催化剂的费托反应性能;采用X射线衍射、比表面积测试、扫描电子显微镜等测试手段分析了介孔分子筛及催化剂的物性特征,分别使用气相色谱质谱联用仪、气相色谱对反应产物进行了定性和定量分析。结果表明:有机硅烷剂中的硅与硅凝胶中的硅摩尔比为1∶30时达到饱和,继续提高硅烷剂浓度将导致分子筛结晶度下降,且大量的微孔损失,粒径明显减小。通过改变有机硅烷剂的取代基链长,分子筛的平均介孔尺寸可在4.9~9.0 nm进行调控。极性有机硅烷剂更有利于合成高结晶度与大比表面积的介孔分子筛,其中最大比表面积达到683.7 m^(2)/g,且相较于相同链长的非极性有机硅烷剂合成的分子筛其微孔孔容增加了约30%,而介孔孔容几乎相同。在以合成气为原料气的费托合成实验中,极性有机硅烷剂合成的分子筛催化剂对柴油段C_(10-20)产物具有较高选择性,最高达31.1%;非极性有机硅烷剂合成的分子筛催化剂对汽油段C_(5-12)产物具有较高选择性,最高达39.7%。

Ti incorporation in MCM-41 mesoporous molecular sieves using hydrothermal synthesis

Abstract Titanium-containing mesoporous materials （Ti-MCM-41） were obtained by hydrothennal synthesis. Such materials are active catalysts for the transesterifica- tion of dimethyl oxalate and phenol to produce diphenyl oxalate. To understand the role of the Ti in the catalytic process, Ti-MCM-41 samples with different Si/Ti ratios （from 5 to 100） were prepared and the samples were analyzed by Fourier transform infrared spectroscopy, UV- visible spectroscopy, and ammonia temperature pro- grammed desorption. It was concluded that the Ti is incorporated into the framework of the MCM-41 and formed weak Lewis acid sites. In addition, the number of Ti（IV） sites increased as the amount of titanium increased. X-ray powder diffraction, N2 adsorpfion-desorption and transmission electron microscopy results showed that the Ti-MCM-41 samples have a hexagonal arrangement of mono-dimensional pores. A large number of Ti（IV） sites coupled with the mesoporous structure and large pore diameters are favorable for the transesterification catalytic properties of Ti-MCM-41.

Synthesis and Characterization of Ordered Mesoporous Aluminosilicate Molecular Sieves with High Stability in High-Temperature Steam

The ordered mesoporous aluminosilicate molecular sieve （MASMS-1） stable in the high-temperature steam has been successfully synthesized from the assembly of diluted ZSM-5-type precursor with mesoporous MCM-41. The material was characterized by XRD, N2 adsorption-desorption, FE-SEM, TEM, FT-IR spectroscopy and 27A1 MAS NMR techniques. This mesoporous material shows high stability in the high-temperature steam [H2O （φ=20%） in N2 at 800 ℃ for 4 h], which might be ascribed to the synergistic effect of both thick walls containing zeolite-like five-membered ring subunits and highly condensed surface silanol groups.

Preparation of Mesoporous Molecular Sieves Al-MSU-S Using Ionic Liquids as Template

Mesoporous molecular sieves Al-MSU-S has been prepared from the precursor of zeolite Y using ionic liquids 1-hexadecane-3-methylimidazolium bromide （CMIMB） as a template in basic medium, which exhibited larger pore diameter, pore volume and surface area than that synthesized using cetyl trimethyl ammonium bromide （CTAB） template.

介孔氧化硅分子筛负载金属氧化物高温煤气脱硫剂结构调控与脱硫过程放硫的研究进展

煤气化是煤炭清洁高效利用的核心技术,但气化粗煤气中所含硫化氢(H_(2)S)会腐蚀设备并污染环境,因此需要对煤气进行净化脱硫。介孔氧化硅分子筛具有大比表面积、大孔容和有序的介孔结构等特性,将其作为金属氧化物的载体可促进金属氧化物的分散,并为脱硫反应提供大量的反应活性位点,减少传质阻力。脱硫剂构效关系是煤气脱硫技术的关键科学难题之一,然而对于负载型高温煤气脱硫剂而言,上述关系受介孔氧化硅分子筛、脱硫活性组分种类、脱硫剂改性手段和脱硫条件等多因素叠加影响,因而要明晰其本质极具挑战。为此,首先探讨了不同介孔氧化硅分子筛的孔道结构特性,剖析了介孔氧化硅分子筛负载活性组分后的脱硫行为差异,发现拥有丰富孔结构及较厚孔壁的载体的脱硫剂在高温脱硫过程中表现更优。同时,分析了近年来针对锌基、锰基和铁基等金属氧化物负载型脱硫剂的结构调控策略及其对脱硫性能的影响规律,认为通过金属掺杂复合改性可提高活性组分脱硫活性;并对脱硫过程中的放硫机制、放硫规律及抑制手段进行了探讨,认为在脱硫剂中引入催化羰基硫(COS)氢解助剂可有效抑制放硫行为。本综述内容可为高性能高温脱硫剂结构设计与功能化构筑提供理论依据。

有序介孔硅材料的微量碳层修饰及VOCs吸附性能

以孔道规整的介孔分子筛SBA-15和MCM-41作为硅基材料前驱体,以蔗糖作为生物质碳源,通过化学刻蚀方法将生物质碳引入两种介孔分子筛孔道中,从而制备获得碳-介孔分子筛复合材料.通过对蔗糖浓度条件的优化,可以获得比表面积、碳含量和甲苯吸附性能最佳的碳-介孔分子筛复合材料.经由TEM-EDS图谱可以证明,碳元素均匀存在于上述两种介孔硅材料的孔道.进一步通过孔径分析,发现碳层修饰后的介孔分子筛(C@MCM和C@SBA)中微孔比例显著提升,因而其甲苯吸附容量明显高于其对应的介孔分子筛(MCM-41和SBA-15).其中,C@SBA在5次吸脱附循环中容量基本保持不变,循环吸附性能相比C@MCM更为优越.此外,碳层修饰后的介孔分子筛具有良好的耐水性,其吸附容量不会随相对湿度的提高而大幅降低.最后,上述复合材料对其他含氧VOCs物种也具有较好的吸附性能,但对甲苯等弱极性分子的吸附效果更显著.

NaY分子筛复合材料及其催化裂化催化剂性能

以高岭土和水玻璃为原料,采用水热法原位晶化合成了NaY分子筛复合材料,通过离子交换法改性并制备出催化裂化催化剂,利用X射线荧光仪、N2吸附-脱附仪、扫描电子显微镜等仪器对试样进行结构表征,在固定流化床微型反应器装置上进行催化剂裂化反应性能评价。结果表明:该NaY分子筛复合材料的外比表面积为93.70 m^(2)/g,介孔孔容为0.19 cm^(3)/g,颗粒直径约在300~500 nm;改性后复合材料的介孔主要分布在2~20 nm,且为双孔分布,分布峰分别为3.8,5.6 nm;与常规NaY型分子筛催化剂相比,采用该NaY型分子筛复合材料所制备的催化剂其反应转化率、液化气和总液体收率依次提高6.18,5.16,1.61个百分点,重油收率下降3.34个百分点,生焦因子下降0.80。

TiO_(2)/SBA-15复合催化剂的制备及其光催化性能研究

本文采用溶胶凝胶法将二氧化钛负载于SBA-15介孔分子筛上,成功制备了TiO_(2)/SBA-15复合催化剂,并将其应用于光催化降解亚甲基蓝的实验中。本研究详细探讨了亚甲基蓝溶液初始质量浓度、pH值、光催化反应时间以及TiO_(2)/SBA-15复合催化剂的投加量等因素对光催化降解效果的影响。